This invention relates to an apparatus and method for cutting rubber material and more particularly for cutting a layer from a substrate length of rubber material. The invention has particular utility in obtaining lengths of rubber material from used conveyor belting which incorporates a layer of steel cords imbedded within a substrate rubber material and also in removing the top layer from such used conveyor belting for the purpose of recovering the belt.
Previous methods and apparatus for cutting a layer from a substrate length of rubber material have involved forcing the material through a fixed knife. Such a technique has met with little success in view of the inherent difficulties in cutting rubber material in a single skiving action. This arises principally as a result of the knife edge of the cutting blade producing a cut in the direction at which it is angled and the continuity of the cut in this direction in spite of attempts made to alter this cutting direction by re-alignment of the material. Consequently, once the cutting direction has gone askew, if the blade itself has not been re-aligned and external forces are applied upon the blade by the material itself to re-align the blade, a tremendous stress is created on the blade causing its eventual destruction. Accordingly, it is necessary to stop the cutting processing and re-position the blade to the desired attitude, immediately upon detecting that the cutting direction has gone askew.
Due to the obvious difficulties involved in precise positioning of the blade to obtain a constant thickness of cut and the necessity of re-aligning the blade to this position once the direction of cut has gone askew, such cutting operations have been limited to cutting conveyor belting having a reinforcing stratum of steel cords. By cutting such materials, it is possible to align the blade so that the knife edge causes a slightly depressed cutting direction so that the blade may encounter the steel cords and effectively run along the top of them to obtain a constant depth of cut. In this manner, the steel cords are sufficiently strong to prevent the knife from penetrating the stratum formed thereby and hence can effectively re-align the blade to cut at a constant depth. Such cutting operatiions, although possible, are still difficult to perform with using a fixed knife due to the limitation in the width of belting which may be cut in a single pass due to the large stresses experienced by the blade. Thus it is generally necessary to limit the cutting operation to conveyor belts of approximately ten to twenty centimeters in breadth. In situations where belts of greater breadth are required to be cut, it is necessary to run a number of passes of the belt through the cutting station enabling successive portions of the belt to be cut until its entire breadth has been cut.
It is an object of the present invention to provide an apparatus and method for cutting a layer from a substrate length of rubber material at a constant depth of cut without the need of stopping the cutting operation and re-aligning the knife edge of the cutting blade.
It is a preferred object of the invention to obtain selectively variable depths of cut independently of the location of a steel cord stratum within the substrate length of material to be cut.